Electric toothbrush with an illumination ring

ABSTRACT

An electric toothbrush includes a grip portion, a brush portion on which a replaceable toothbrush is mounted, and an illumination ring between the grip portion and the brush portion. The brush portion is inclined with respect to the grip portion. The illumination ring is provided around the toothbrush, so that a user can view the illumination ring no matter what angle he/she is holding the toothbrush.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication Serial No. 2016-051473, filed Mar. 15, 2016, the entirety ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an electric toothbrush having a gripportion and a brush portion, and more particularly, to the structure ofthe electric toothbrush.

Description of Related Art

The electric toothbrush in the market has the grip portion and the brushportion with an indicator located in the grip portion. Also, theelectric toothbrush in the market has the brush portion angled orinclined with respect to the grip portion. Such an electric toothbrushis disclosed, for example, in US Patent Publication No. 2011-0056033(corresponding to Japanese Patent Publication No. 2009-268828).

According to US Patent Publication No. 2011-0056033, the indicator isprovided on only one side of the electric toothbrush where the bristleis provided, so that the user can view the indicator only when theelectric toothbrush is held at a certain angle. It is difficult for theuser to see the indicator when the electric toothbrush is held insideways, particularly when the user is brushing the inside surface ofthe tooth.

Also, according to US Patent Publication No. 2011-0056033, since thebrush portion is inclined with respect to the grip portion, the tensionobserved at a joint between the grip portion and brush portion will berelatively high, particularly when the user pushes the brush hardagainst the teeth. There is no detailed description in US PatentPublication No. 2011-0056033 on the structure of connection between thegrip portion and the brush portion.

BRIEF SUMMARY OF THE INVENTION (1) Problems to be Solved

The prior art electric toothbrush has a problem that the indicatorcannot be viewed by the user, as explained above. An object of thepresent invention is to provide an electric toothbrush which has anindicator that can be viewed by the user regardless of the holding angleof the electric toothbrush.

(2) Means for Solving the Problems

According to the present invention, an electric toothbrush having anelongated grip portion and an elongated brush portion comprises: anillumination ring body having an illumination ring located between thegrip portion and the brush portion; a light emitting element provided inthe grip portion for emitting light rays; a circuit board provided inthe grip portion, said circuit board having a controller which isconfigured to control ON and OFF states of the light emitting element.

According to an embodiment, the illumination ring body includes acylindrical body and an internal plate located inside the cylindricalbody with an opening formed therein, wherein a portion of thecylindrical body located below the internal plate defines a skirt, andthe illumination ring is provided on the outside of the cylindrical bodyin a form of a ring.

According to an embodiment, the circuit board includes an elongatedboard and a light emitting element holding plate connected to theelongated board, and wherein the light emitting element is provided onthe light emitting element holding plate such that the light raysemitted from the light emitting element direct in an axial direction ofthe elongated grip portion.

According to an embodiment, the electric toothbrush further comprises: aslanted surface slanted in a direction of light rays from the lightemitting element such that the light rays reflected on the slantedsurface enter into the cylindrical body through the skirt of theillumination ring body and emit out from the illumination ring.

According to an embodiment, the electric toothbrush further comprises: achassis which is provided in the grip portion and supports the circuitboard.

According to an embodiment, the slanted surface is formed on thechassis.

According to an embodiment, the slanted surface is formed on theillumination ring body.

According to an embodiment, the controller controls the light emittingelement to emit light rays when a bristle of the electric toothbrush isheld at about 45 degrees above or below a plane level.

According to an embodiment, the circuit board further has anacceleration sensor which is configured to detect an angle of theelectric toothbrush held by a user, whereby the controller controls thelight emitting element based on a signal produced from the accelerationsensor.

According to the electric toothbrush of the present invention, the usercan see the indicator, which is the illumination ring, regardless of theholding angle of the electric toothbrush.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side view of an electric toothbrush according to anembodiment of the present invention.

FIG. 2 is an exploded view of the electric toothbrush shown in FIG. 1.

FIG. 3 is a perspective view of a circuit board shown in FIG. 2.

FIG. 4 is a perspective partial view of a chassis shown in FIG. 2.

FIG. 5A is a side view of an illumination ring body shown in FIG. 2.

FIG. 5B is a top plan of the illumination ring body shown in FIG. 5A.

FIG. 6 is a cross-sectional view of the illumination ring body takenalong line VI-VI shown in FIG. 5B.

FIG. 7 is a cross-sectional partial view of the electric toothbrushshown in FIG. 1.

FIG. 8 is a cross-sectional partial view taken along line VIII-VIIIshown in FIG. 7.

FIG. 9 is a cross-sectional partial view taken along line XI-XI shown inFIG. 8.

FIG. 10 is a side view of a stem joint shown in FIG. 2.

FIG. 11 is a cross-sectional view of the stem joint shown in FIG. 10.

FIG. 12 is a perspective view of the stem joint shown in FIG. 11.

FIG. 13 is an exploded view of the stem joint and the stem.

FIG. 14 is a side view of the stem joint and the stem in the connectedcondition.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an electric toothbrush 1 according to an embodimentof the present invention is shown. The electric toothbrush 1 has a gripportion 2 and a brush portion 4. An axis X4 of the brush portion 4 isangled or inclined a predetermined angle θ, such as for example but notlimited to between about 6 and about 10 degrees, most preferably about 8degrees, with respect to an axis X2 of the grip portion 2 so that abristle portion 4 a of the brush portion 4 can be easily held against auser's tooth when the grip portion 2 is held by the user proximate theuser's mouth. As will be discussed below, the axis X4 and the axis X2can be considered to be defined by the upper cylinder portion 42 a andthe lower cylinder portion 42 b of the stem joint 42, respectively, incertain embodiments.

Referring to FIG. 2, an exploded view of the electric toothbrush 1 isshown. The grip portion 2 of the electric toothbrush 1 includes anelongated body cover 10, a chassis 20, a battery holder 16, a motorsupport 62, and an elongated circuit board 50. An intermediate portionincluding an illumination ring body 30, a stem joint arrangement 40, anda top cover 12, is positioned between and arranged to couple the gripportion 2 to the brush portion 4. The electric toothbrush furtherincludes a stem 80 that is connected to and extends from theintermediate portion. The stem 80 accommodates a DC motor 60 having acylindrical body, and a vibration shaft 70. A top rubber cover 14 isalso provided as part of the intermediate portion. The brush portion 4includes a replaceable brush 90. A battery to be inserted in the batteryholder 16 is a rechargeable battery or a dry cell battery. Thereplaceable brush 90 is detachably mounted on the stem 80. Thereplaceable brush 90 covers the stem 80 completely or partially.

In the specification, the term “top” or “upper” refers to the side ofthe electric toothbrush 1 where the replaceable brush 90 is provided,and the term “bottom” or “lower” refers to the side where the batteryholder 16 is provided, such as shown in FIG. 1.

The body cover 10 has an interior cavity, which may be for example,cylindrical, for accommodating the chassis 20, battery holder 16 andcircuit board 50. The body cover 10 has a top side and a bottom sideopened. The body cover 10 is capable of being gripped or grasped by auser.

As shown in FIG. 3, the circuit board 50 has an elongated board 52 and alight emitting element support plate which is a U-shaped plate 54 firmlyconnected to a top end of the elongated board 52. The U-shaped plate 54has two arms 54 a and 54 b extending perpendicularly from the top end ofthe elongated board 52. Two light emitting elements, such aslight-emitting diodes (LEDs) 56 a and 56 b are mounted on one arm 54 a,and another two LEDs 56 c and 56 d are mounted on other arm 54 b, sothat four LEDs 56 a, 56 b, 56 c and 56 d are located, when viewed fromthe top, at four corners of a rectangle, or a square. While four LEDs 56a, 56 b, 56 c and 56 d are shown and described here, more or fewer LEDsmay be located on the plate 54. Moreover, the LEDs may be discrete LEDsources or they could include one or more flexible printed or organicLED substrates capable of illumination. Turning ON and OFF of the LEDs56 a, 56 b, 56 c and 56 d are controlled by a controller mounted on thecircuit board 50. The controller includes a micro-processor and anacceleration sensor. The acceleration sensor is used for detecting theangle of the toothbrush held by a user. As shown in FIG. 2, a connector58 extends through the center of the U-shaped plate 54 for electricalconnection with the DC motor 60.

Referring to FIG. 4, a top portion of chassis 20 is shown. Chassis 20has a pair of fingers 22 a and 22 b for holding the elongated board 52,a pair of shoulders 24 a and 24 b, and a neck portion 26. The neckportion 26 has a center hole in the direction of axis X2, with recesses26 a and 26 b formed at opposite sides thereof. Through-holes 28 and 29are formed, respectively, under the shoulders 24 a and 24 b. Thethrough-holes 28 and 29 have bottom surfaces 28 a and 29 a,respectively, which are flattened for receiving thereon, respectively,the two arms 54 a and 54 b of the U-shaped plate 54.

The two arms 54 a and 54 b of the U-shaped plate 54 are inserted in thethrough-holes 28 and 29, respectively, as shown in FIG. 2, and theelongated board 52 is firmly held between the fingers 22 a and 22 b.Also, the connector 58 extends through the center hole in the neckportion 26. When the arms 54 a and 54 b of the U-shaped plate 54 areplaced on bottom surfaces 28 a and 29 a of the through-holes 28 and 29,the LEDs 56 a, 56 b, 56 c and 56 d on the two arms 54 a and 54 b facethe top, i.e., in the direction of axis X2.

The through-holes 28 and 29 further have top slanted surfaces 28 b and29 b which are for reflecting purposes and are angled about 45 degreeswith respect to the direction of axis X2 so that light rays emitted fromthe LEDs, particularly, from 56 a and 56 c reflect on the slantedsurfaces 28 b and 29 b, and direct outwardly in a radial or otherwisesubstantially perpendicular direction with respect to the axis X2. InFIG. 4, only two slanted surfaces 28 b and 29 b are shown, but there aretwo more slanted surfaces 28 c and 29 c on the other side in FIG. 4. Theslanted surfaces 28 b, 28 c, 29 b and 29 c are angled about 45 degreeswith respect to axis X2 in radial direction, so that slanted surfaces 28b, 28 c, 29 b and 29 c are arranged in a manner similar to an umbrellasurface. Each of the slanted surfaces 28 b, 28 c, 29 b and 29 c is flat,but it may be curved. The light rays emitted from the LEDs 56 a, 56 b,56 c and 56 d in the direction of axis X2 are reflected on the slantedsurfaces 28 b, 28 c, 29 b and 29 c, and are further directed in theradial direction or otherwise substantially perpendicular with respectto the axis X2.

Referring to FIGS. 5A and 6, the illumination ring body 30 is shownwhich is made of a substantially transparent or translucent material,such as synthetic resin. The illumination ring body 30 has hollowcylindrical body 30 a with an illumination ring 30 b circumferentiallysurrounding the cylindrical body 30 a. The illumination ring 30 b is anannular structure that protrudes from the outer surface of theillumination ring body 30, thereby forming an annular flange. Theillumination ring 30 b is inclined or angled a predetermined angle θ,such as for example but not limited to between about 6 degrees and about10 degrees, most preferably about 8 degrees, with respect to a planeperpendicular to the axis X2. The cylindrical body 30 a, which is a partof the grip portion 2, has opposite ends opened, and has an internalplate 30 c inside the cylindrical body 30 a so as to provide a skirtwall 30 d below the internal plate 30 c. The center of the internalplate 30 c is formed with an opening 30 e (FIG. 5B) in a shape ofsimi-circle to fittingly match the semi-circle cross-section of the neckportion 26 with recesses 26 a and 26 b, as best shown in FIG. 8. Abovethe internal plate 30 c, the cylindrical body 30 a has a receivingopening 30 i for fittingly receiving a lower cylinder portion 42 b ofthe stem joint 42 covered with a bottom rubber cover 46, as will bedescribed later. While the illumination ring body 30, including thecylindrical body 30 a and illumination ring 30 b, is shown and describedas being cylindrical, one of skill in the art will recognize that othershapes and geometries are possible depending on the shape and design ofthe grip portion 2 of the electric toothbrush 1.

As shown in FIG. 5B, on the top surface of the internal plate 30 c,there are three blocks 30 f, 30 g and 30 h formed at corners between theinternal plate 30 c and the cylindrical body 30 a.

On the outside of the illumination ring body 30, a pair of projections30 p are provided, as shown in FIG. 5A.

The chassis 20 provided with the circuit board 50 is inserted into thebody cover 10 from the bottom opening, and held inside the body cover 10at a position shown in FIG. 4, so that the top end of the chassis 20stays a little below the top opening of the body cover 10.

As shown in FIGS. 7 and 8, the illumination ring body 30 is mounted onthe shoulders 24 a and 24 b of the chassis 20 such that neck portion 26of the chassis 20 is fittingly inserted into the opening 30 e. At thisposition, the bottom surface of the internal plate 30 c rests on theshoulders 24 a and 24 b of the chassis 20, and the skirt wall 30 dcircumferentially surrounds, at least in part, the slanted surfaces 28b, 28 c, 29 b and 29 c. The outer surface of the illumination ring body30 below the illumination ring 30 b is fittingly inserted into the topopening of the body cover 10 such that the projections 30 p on theillumination ring body 30 engage with complementary recesses (not shown)formed on the inside surface of the body cover 10 to couple the bodycover 10 to the illumination ring body 30.

As shown in FIG. 9, the light emitted from the LEDs, such as 56 a and 56b, reflects on the slanted surfaces 28 b and 28 c, and direct toward theskirt wall 30 d, so that the light is optically transmitted withininside and throughout the illumination ring body 30. Some of this lightwill be transmitted into the illumination ring 30 b and exit an outerannular surface of the illumination ring 30 b that forms a portion ofthe exposed outer surface of the electric toothbrush.

As shown in FIG. 7, a majority of the illumination ring body 30 isconcealed such that the portion below the illumination ring 30 b isconcealed by body cover 10, and the portion above the illumination ring30 b is concealed by top cover 12. Body cover 10 and top cover 12 mayboth be substantially opaque and may be made from the same or differentmaterials. In this embodiment, only the illumination ring 30 b can beviewed directly from the outside of the electric toothbrush 1.

The outside surface of the illumination ring body 30, with the exceptionfor the illumination ring 30 b, can be coated with a reflector paint sothat light that has entered the illumination ring body 30 from theinside surface of the skirt wall 30 d can be maintained within theillumination ring body 30 until said light can exit the illuminationring 30 b. Stated simply, the reflector paint will prevent and/orminimize leakage of light. Thus, light from the illumination ring 30 bcan be outputted with high intensity outside the electric toothbrush 1.

Since the illumination ring 30 b is provided in a viewable mannercompletely, i.e., 360 degrees, around the electric toothbrush 1 justabove the grip portion 2, it is possible for the user to view thelighting of the illumination ring 30 b no matter which angle theelectric toothbrush 1 is held. It should be noted, however, that whilethe illumination ring 30 b is an annular continuous structure in theillustrated embodiment, in other embodiments the illumination ring 30 bmay be in the form of spaced-apart segments that collectively define asegmented ring structure.

The lighting of the illumination ring 30 b can be effected in variousoccasions in various modes, as explained below.

The first occasion is when a bristle portion of the electric toothbrush1 is held at about 45 degrees above or below the plane level so that thebristle touches the tooth pockets of the upper or lower tooth from theoutside or inside the tooth.

The second occasion is when the electric toothbrush 1 is held at about90 degrees above or below the plane level so that the bristle touchesthe occlusal surface of the molar or pre-molar tooth.

The third occasion is when the electric toothbrush 1 is held at aboutthe plane level so that the bristle touches the front face or back faceof the tooth perpendicularly.

Each of the above occasions can be detected by the acceleration sensorin a manner disclosed, for example, in U.S. Publication No. 2012/0251975(corresponding to Japanese Publication No. JP2011-156204) or JapanesePublication JP2009-291316, which are herein incorporated by reference inits entirety.

The lighting mode can be changed with respect to different occasions.For example, a first lighting mode can be an ON and OFF mode such thatthe LEDs are turned ON when the above explained target angle isdetected.

A second lighting mode can be a graduation variable mode such that theLEDs change the strength of the light (i.e., the intensity of the light)to glow brighter as the toothbrush angle reaches the target angle.

A third lighting mode can be a blinking mode such that the frequency ofON and OFF of the LEDs becomes higher as the toothbrush angle reachesthe target angle.

In one embodiment, the lighting can be effected only in one of the threeoccasions explained above using any one of the three lighting modes.

Referring to FIG. 2, the stem joint arrangement 40 includes a stem joint42, a stem packing 44 and a bottom rubber cover 46.

Referring to FIGS. 10 and 11, the stem joint 42 has an upper cylinderportion 42 a and a lower cylinder portion 42 b. The upper cylinderportion 42 a has its axis aligned with axis X4, and the lower cylinderportion 42 b has its axis aligned with axis X2.

The upper cylinder portion 42 a has an inside surface formed with femalescrew groove 42 c. The top surface of the upper cylinder portion 42 a isformed with a slanted projection 42 d and a stopper projection 42 e. Theslanted projection 42 d has one side formed with a slanted wall and theother side formed with an upright wall. The stopper projection 42 e hasopposite sides formed with upright walls. A receiving recess 42 f, whichis a second engage member (a first engage member will be describedlater), is formed adjacent the screw groove 42 c, such as between theprojections 42 d and 42 e, particularly between the upright wall of theslanted projection 42 a and the upright wall of the stopper projection42 e.

Referring to FIG. 12, the lower cylinder portion 42 b has a recessedring portion 42 g and three legs 42 h, 42 i and 42 j. As shown, legs 42i and 42 j are mirror images of one another and together are positioneddiametrically opposite the leg 42 h. An indent 42 k is formed betweenlegs 42 h and 42 i. An indent 42 l is formed between legs 42 h and 42 j.An indent 42 m is formed between legs 42 i and 42 j.

The stem packing 44 as shown in FIGS. 2 and 7, made of rubber or a likematerial, is fittingly inserted in the recessed ring portion 42 g (seeFIGS. 10-12). The bottom rubber cover 46 as shown in FIGS. 2 and 7 isfittingly mounted on the lower cylinder portion 42 b covering each ofthe legs 42 h, 42 i and 42 j separately (see FIGS. 10-12). Accordingly,indents 42 k, 42 l and 42 m appear on the outside of the bottom rubbercover 46.

Next, the connection between the lower cylinder portion 42 b and theillumination ring body 30 is explained.

With reference to FIGS. 2 and 7, the lower cylinder portion 42 b mountedwith the bottom rubber cover 46 is fittingly inserted in the receivingopening 30 i of the hollow cylindrical body 30 a of the illuminationring body 30 such that indents 42 k, 42 l and 42 m existing on theoutside of the bottom rubber cover 46 fittingly receive three blocks 30g, 30 h and 30 f, respectively. Accordingly, the lower cylinder portion42 b is prevented from being freely rotated in the hollow cylindricalbody 30 a.

As shown in FIG. 7, stem 80 has an elongated cavity 86 for receiving avibration generator including the vibration shaft 70 and the DC motor60. The vibration shaft 70 includes an extension shaft 72 made, forexample, of synthetic resin, such as POM (polyoxymethylene), and aneccentric shaft 73 which may be, for example, made of metal. Theextension shaft 72 of the vibration shaft 70 includes a collar portion74 provided close to a bottom end, a resilient shaft portion 75 and aconnecting portion 76 which are integrally formed by synthetic resin.The bottom end face of the extension shaft 72 is formed with a recess tobe engaged with a shaft of the DC motor 60. DC motor 60 has two wiresextending from a bottom face thereof for electric connection with thecircuit board 50 through connector 58. The vibration shaft 70 and the DCmotor 60 are placed in the elongated cavity 86 and held in the cavity bythe motor support 62.

The eccentric shaft 73 of the vibration shaft 70 includes an eccentricportion 77 and an axial shaft portion 78. The bottom end of theeccentric portion 77 is firmly connected to the connecting portion 76 bymolding and the upper end of the eccentric portion 77 is provided withthe axial shaft portion 78.

When the vibration shaft 70 rotates about its axis by the DC motor 60,the eccentric portion 77 generates a high frequency vibration which istransmitted to the stem 80 and to the brush 90. The resilient shaftportion 75 has a flexibility to receive the high frequency vibration ofthe eccentric portion 77.

Stem 80 is also formed by synthetic resin, such as for example, POM. Arecessed hole 87 is formed at the end of the elongated cavity 86. Therecessed hole 87 slidably receives the axial shaft portion 78. Theelongated cavity 86 accommodates therein the vibration shaft 70 and theDC motor 60. The vibration shaft 70 is freely rotated in the elongatedcavity 86. The recessed hole 87 serves as a bearing for freely holdingthe axial shaft portion 78. The vibration shaft 70 freely rotates insidethe elongated cavity 86 even under high frequency vibration.

Since the recessed hole 87 serves as the bearing, it is not necessary toprovide a separate bearing arrangement for rotatably holding the axialshaft portion 78.

Referring to FIG. 13, a lower end portion of the stem 80 is shown indetail. Stem 80 includes a collar 82, and a male screw groove 84 belowthe collar 82. A projection 85, which is a first engage member, isformed adjacent the screw groove 84, such as immediately under thecollar 82, i.e., near the end of the screw groove 84.

Stem 80 is firmly connected to the stem joint 42 such that the malescrew groove 84 of stem 80 is driven into the female screw groove 42 cof the stem joint 42, as the stem 80 rotates about its axis X4. When thestem 80 rotates a predetermined number of turns, the projection 85,which is the first engage member, slides over the slanted wall of theslanted projection 42 d, and falls into the receiving recess 42 f, whichis the second engage member, as best shown in FIG. 14. At this point,stem 80 is prevented from a further rotation in either direction and isretained at a desired and predetermined rotated position from theviewpoint of balance as well as to ensure that the brush 90 is properlyoriented relative to the grip portion 2 when attached. The projection85, which is the first engage member, and the receiving recess 42 f,which is the second engage member, can be formed in oppositerelationship, or any other engaging or retaining arrangement can beused. The male and female screw grooves 84 and 42 c can be provided inopposite relationship.

As shown in FIGS. 2 and 7, the top rubber cover 14 is mounted on thestem 80 such that the bottom face of the top rubber cover 14 abutsagainst the upper surface of the collar 82. Then, the top cover 12 ismounted on the stem 80 such that the bottom face of the top cover 12abuts against the upper surface of the illumination ring 30 b.

According to an embodiment, suitable bonding agent is used in at leastin one or more of the following instances: (a) between elongated bodycover 10 and illumination ring body 30, (b) between illumination ringbody 30 and stem joint 42, and (c) between stem joint 42 and stem 80.

According to the above described embodiment, the slanted surfaces 28 b,28 c, 29 b and 29 c are provided in the chassis 20, but can be providedat any other places, such as at the bottom surface of the internal plate30 c of the illumination ring body 30. In still another embodiment, theslanted surfaces may be omitted and the light emitting elements 56 a-dwill be arranged to emit light directly into the illumination ring body30. Additionally, while the illumination ring 30 b is illustrated asbeing between the grip portion 2 and the brush portion 4, and morespecifically the grip portion 2 and the intermediate portion, in otherembodiment, the illumination ring 30 b may be located at a lowerposition and entirely within the grip portion 4 or entirely within theintermediate portion.

INDUSTRIAL APPLICABILITY

The electric toothbrush can be used for oral health care.

KEYS TO THE REFERENCE NUMBERS

1 . . . electric toothbrush, 2 . . . grip portion, 4 . . . brushportion, 10 . . . body cover, 12 . . . top cover, 14 . . . top rubbercover, 16 . . . battery holder, 20 . . . chassis, 22 a, 22 b . . .fingers, 24 a, 24 b . . . shoulders, 26 . . . neck portion, 26 a, 26 b .. . recesses, 28, 29 . . . through-holes, 28 b, 28 c, 29 b, 29 c . . .slanted surfaces, 30 . . . illumination ring body, 30 a . . .cylindrical body, 30 b . . . illumination ring, 30 c . . . internalplate, 30 d . . . skirt wall, 30 e . . . opening, 30 f, 30 g, 30 h . . .blocks, 40 . . . stem joint arrangement, 42 . . . stem joint, 42 c . . .female screw groove, 42 d . . . slanted projection, 42 e . . . stopperprojection, 42 h, 42 i, 42 j . . . legs, 42 k, 42 l, 42 m . . . indents,44 . . . stem packing, 46 . . . bottom rubber cover, 50 . . . elongatedcircuit board, 52 . . . elongated board, 54 . . . U-shaped plate, 56 a,56 b, 56 c, 56 d . . . LEDs, 60 . . . DC motor, 62 . . . motor support,70 . . . vibration shaft, 80 . . . stem, 90 . . . replaceable brush

The invention claimed is:
 1. An electric toothbrush having an elongated grip portion (2) and an elongated brush portion (4), said electric toothbrush comprising: an illumination ring body (30) having an illumination ring (30 b); a light emitting element (56 a, 56 b, 56 c, 56 d) for emitting light rays; a circuit board (50) provided in the grip portion (2), said circuit board (50) having a controller which is configured to control ON and OFF states of the light emitting element; wherein said illumination ring body (30) includes a cylindrical body (30 a) and an internal plate (30 c) located inside the cylindrical body (30 a) with an opening (30 e) formed therein, wherein a portion of the cylindrical body (30 a) located below the internal plate (30 c) defines a skirt (30 d), and the illumination ring (30 b) is provided on the outside of the cylindrical body (30 a) in a form of a ring; and wherein said circuit board (50) includes an elongated board (52) and a light emitting element holding plate (54) connected to the elongated board (52), and wherein the light emitting element (56 a, 56 b, 56 c, 56 d) is provided on the light emitting element holding plate (54) such that the light rays emitted from the light emitting element direct in an axial direction of the elongated grip portion.
 2. The electric toothbrush as claimed in claim 1, further comprising: a slanted surface (28 b, 28 c, 29 b, 29 c) slanted in a direction of light rays from the light emitting element (56 a, 56 b, 56 c, 56 d) such that the light rays reflected on the slanted surface enter into the cylindrical body (30 a) through the skirt (30 d) of the illumination ring body (30) and emit out from the illumination ring (30 b).
 3. The electric toothbrush as claimed in claim 2, further comprising: a chassis (20) which is provided in the grip portion (4) and supports the circuit board (50).
 4. The electric toothbrush as claimed in claim 3, wherein the slanted surface (28 b, 28 c, 29 b, 29 c) is formed on the chassis (20).
 5. The electric toothbrush as claimed in claim 3, wherein the slanted surface (28 b, 28 c, 29 b, 29 c) is formed on the illumination ring body (30).
 6. The electric toothbrush as claimed in claim 1, wherein the controller controls the light emitting element to emit light rays when a bristle of the electric toothbrush is held at about 45 degrees above or below a plane level.
 7. The electric toothbrush as claimed in claim 1, wherein the circuit board further having an acceleration sensor which is configured to detect an angle of the electric toothbrush held by a user, whereby the controller controls the light emitting element based on a signal produced from the acceleration sensor.
 8. The electric toothbrush as claimed in claim 1, wherein the illumination ring (30 b) is located between the grip portion (2) and the elongated brush portion (4).
 9. The electric toothbrush as claimed in claim 1, wherein the light emitting element (56 a, 56 b, 56 c, 56 d) is located in the grip portion (2). 